The invention relates generally to control of a permanent magnet motor. More particularly, the invention relates to a technique for control of a permanent magnet motor without the use of a position sensor.
A three phase permanent magnet motor may be controlled by supplying three phase power to stator windings in the motor. Control schemes for a permanent magnet motor may involve tracking the rotor position of the motor. While mechanical position sensors coupled to the rotor may effectively provide motor position information, the presence of mechanical sensors may reduce the mechanical dependability of the system. Moreover, techniques without mechanical position sensors may require high frequency injection or back electromotive force (EMF) to identify the rotor position, may depend on upon the saliency of the motor, or may not function for both a surface-mount permanent magnet motor and an interior permanent magnet motor.